1. Field of the Invention
The present invention generally relates to fluid dispensing systems and methods of dispensing that are applicable to imprint lithography processes.
2. Description of the Relevant Art
Imprint lithography is a technique that is capable of printing features that are smaller than 50 nm in size on a substrate. Imprint lithography may have the potential to replace photolithography as the choice for semiconductor manufacturing in the sub-100 nm regime. Several imprint lithography processes have been introduced during 1990s. However, most of them have limitations that preclude them from use as a practical substitute for photolithography. The limitations of these prior techniques include, for example, high temperature variations, the need for high pressures and the usage of flexible templates.
Recently, imprint lithography processes may be used to transfer high resolution patterns from a quartz template onto substrate surfaces at room temperature and with the use of low pressures. In the Step and Flash Imprint Lithography (SFIL) process, a rigid quartz template is brought into indirect contact with the substrate surface in the presence of light curable liquid material. The liquid material is cured by the application of light and the pattern of the template is imprinted into the cured liquid. Using a rigid and transparent template makes it possible to implement high resolution overlay as part of the SFIL process. Also the use of a low viscosity liquid material that can be processed by light curing at low pressures and room temperatures lead to minimal undesirable layer distortions. Such distortions can make overlay alignment very difficult to implement.
Air bubbles and localized deformation may cause major defects in the devices manufactured by imprint lithography. The high imprinting pressure used in some imprinting processes may cause distortions that may make overlay alignment extremely difficult. The small areas and volumes of fluid used in imprint lithography at the sub-100 nm level may make the application of such volumes important for the success of the lithography.
Prior art process for adding thin layers of fluids to a substrate involve the use of spin coating methods. Spin coating methods rely on the application of a relatively high viscosity (e.g., greater than about 20 centipoise (cps)) liquid to a substrate. The use of high viscosity liquid allows the even distribution of fluid on a substrate when using a spin coating system without significant loss of fluid during the process. Low viscosity fluids (e.g., viscosities less than about 20 cps), when used in a spin coating system tend to disperse too quickly and may give uneven coatings, coatings that are too thin, or coatings that evaporate quickly. Thus, spin coating processes may be undesirable for the application of a low viscosity liquid to a substrate.